1. Field of the Invention
The invention relates to the technical field of devices capable of coupling the free ends of a bracelet, especially but not exclusively, a watch bracelet.
Essentially, two major types of means capable of allowing bracelets to be closed can be distinguished. In a first simplified embodiment, one of the ends of the bracelet has a buckle in which the end of the other strap of the bracelet, perforated with several holes capable of cooperating with the articulated hook of the buckle, is engaged. This type of closure is generally reserved for a bracelet made of leather, plastic, fabric and, more generally, any relatively flexible material.
In contrast, this solution is not applicable to rigid or semi-rigid bracelets, such as those composed of a plurality of articulated links, for example. In this case, a clasp coupled in an articulated manner to the free ends of the straps of the bracelet is used. This clasp has different types of provision making it possible to bring the straps of the bracelet together and to keep them in a contiguous position corresponding to closure as such. The invention relates to this second type of closure.
2. Description of the Related Art
More particularly, the invention relates to a clasp of the unfolding type, as emerges, for example, from the teaching of Swiss patent CH 633 698 and French patent FR 2 619 292.
In patent CH 633 698, the clasp comprises two arms coupled at one of their ends, in a freely articulating manner, to each of the straps of the bracelet. The two arms are linked together by a linking element, thereby being mounted so as to pivot at each of the ends of said element. The linking element has two notches in the shapes and dimensions corresponding to those of the arms so that the arms are entirely included in the thickness of said element when the bracelet is in the closed position. A catching system is formed at the free ends of the arms and cooperates with complementary provisions formed in the parts connecting the two notches.
This solution is not completely satisfactory, given that it is difficult to adjust the bracelet closure. Furthermore, the catching system, both when closing and opening the bracelet, is impractical to handle.
Patent FR 2,619,292 describes an unfolding clasp having a central element defining two parallel branches. These two branches accommodate, at each of their ends, in a freely articulating manner, two arms on which the straps of the bracelet are assembled. In the closed position, the arms are partially included in the thickness of the central element. To provide locking in the closed position, each arm has, at its free end, a lip capable of catching onto two rods placed transversely between the branches of the central element.
It is therefore necessary to provide a specific shape at the ends of the arms. Here again, difficulties appear with coupling and uncoupling. The arms operate by elasticity and by sliding.
The aim of the invention is to overcome these drawbacks, in a simple, reliable, effective and rational manner.
The problem which the invention aims to solve is to produce a clasp of simplified design and low cost price, while being shaped in order to close the bracelet in an accurate and adjustable manner, and having the option of making it from various materials.
To solve this problem, an unfolding clasp has been designed and made, of the type comprising a profiled plate having two spaced-apart parallel branches defining a space for the assembly, in a freely articulating manner, of at least one blade having, on the side away from its articulating part, provisions for the articulated assembly of part of the bracelet.
According to one feature on which the invention is based, the blade or blades of the bracelet are equipped, close to the part receiving the bracelet, with two rotating rollers placed coaxially with and protruding from each lateral side of the blade in order to cooperate with the profiled rim of an open recess formed laterally in the thickness of each branch for the purpose of creating, after folding down of the blade, a snap-fastening effect by rolling friction resulting from tensioning of the blade, said recess being equipped with means capable of providing the stop for part of the blade or blades in the snap-fastened position, corresponding to the closure position of the bracelet.
Advantageously, the invention relates to an unfolding double clasp. With this aim, the clasp has two opposed symmetrical blades articulated to each of the ends of said branches, the recess being formed substantially in the central part of said branches.
Given these technical features, the result thereof is that by exerting pressure at the end of the blades corresponding to a pressing force, and when the neutral point of snap-fastening, corresponding to the passage of the rotating rollers over the profiled edge of the recess, is exceeded, the automatic snap-fastening of the clasp is obtained in a concomitant manner. The radius of the blades increases.
According to another feature, the means of stopping the blades in the snap-fastened position consist of transverse rollers assembled between the lateral edges of the recess, thereby acting as a spacer.
Advantageously, the clasp has two rollers which are mutually parallel and parallel to the spindle of the rotating rollers of the blades.
Similarly, the profiled plate assembly can be produced as a single piece, such that the means of stopping the blades in the snap-fastened position consist of at least one transverse branch formed directly during the manufacture of said plate, thereby being positioned substantially in the central part of the recess.
To solve the problem set of stopping the blades while allowing them to be handled, the ends of the blades away from their articulation have a profiled shape oriented at an angle above the rotating rollers, thereby being capable of pressing on the spacer rollers, said shapes being arranged in a substantially contiguous manner in the snap-fastened position of the blades.
In this closure position, the blades are completely integrated into the thickness of the space resulting from spacing the two branches.
To solve the problem set of ensuring the coupling of the two straps of the bracelet, the free ends of the profiled shapes are perforated transversely straight through the assembly, with articulation of the corresponding parts of the bracelet.
To solve the problem set of decreasing costs and of facilitating the assembly of the entire clasp, the spacer rollers consist of a tube placed between the lateral edges facing the recess, thereby being assembled on a hollow spindle engaged in the thickness of the branches, said spindle accommodating, at each of its ends, detachable means for translational locking.
To solve the problem set of being able to increase or decrease the snap-fastening force as desired, the coaxial snap-fastening rollers are mounted so as to rotate on a common spindle with the capacity to be dismantled in order to adjust their diameter to the desired snap-fastening force.